Floating structure

Abstract

A floating structure 120 comprises: a floating body 130 which is floatable in a liquid (water 114); a first space 142 which is provided in a portion of the floating body 130 that is in contact with the water 114; a second space 144 which is provided inside the floating body 130 and paired with the first space 142; a damping member (orifice 150) which has at least one communication hole 152 that communicates between the first space 142 and the second space 144; and a sound absorbing material 160 which is provided in at least the second space 144, wherein the first space 142 and the second space 144 accommodate a gas (air) that can change in a compression level by receiving vibrations from the water 114.

Description

Floating Structures

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2024-135003, filed on August 13, 2024, the contents of which are incorporated herein by reference.

[0002] Floating structures have been known in the past that ensure seismic isolation by floating the structure in a fluid. It is generally known that the seismic isolation effect of such floating structures is high in the horizontal direction.

[0003] Furthermore, in order to enhance the seismic isolation performance of a floating structure in the vertical direction, for example, Patent Document 1 discloses providing an air chamber at the bottom of the floating structure and arranging an orifice in the air chamber. By arranging an orifice in the air chamber, resistance is generated when air passes through the orifice. This resistance acts as a damping force in the vibration response caused by the transmission of seismic waves to the floating structure. This damping force can suppress the vibration response of the floating structure caused by the transmission of seismic waves.

[0004] Patent Application No. 2020-095752

[0005] However, when an air chamber is provided at the bottom of a floating structure and the air in the air chamber is vibrated by seismic waves, air column vibration occurs. If the air contained in the air chamber in the floating structure is likened to an air column in a tube, the air column forms standing waves in the tube, causing air column resonance, which is called air column vibration. This air column vibration generates sound, and when the generated sound is transmitted to an object, the object vibrates. The vibration of the object caused by this sound is called acoustic vibration. When the air in the air chamber is vibrated in this way, causing air column vibration and acoustic vibration, the seismic isolation performance of the floating structure may be reduced.

[0006] The present disclosure aims to suppress a decline in the seismic isolation performance of a floating structure.

[0007] In order to solve the above problems, a floating structure as one aspect of the present disclosure comprises a float capable of floating on liquid, a first space provided in a portion of the float that comes into contact with the liquid, a second space provided inside the float and paired with the first space, a damping member having at least one communication hole that connects the first space to the second space, and sound-absorbing material provided in at least the second space, wherein the first space and the second space are spaces that contain gas that can be compressed and changed by receiving vibrations from the liquid.

[0008] The damping member may be an orifice disposed between the first space and the second space.

[0009] The sound absorbing material may be a perforated or porous plate having holes smaller than the through holes.

[0010] A protective film having liquid-proof properties may be provided on at least a part of the surface of the sound-absorbing material.

[0011] The sound absorbing material may be provided on the surface of the damping member.

[0012] A plurality of pairs of first spaces and second spaces may be provided inside the floating body.

[0013] According to the present disclosure, it is possible to suppress a decrease in the seismic isolation performance of a floating structure.

[0014] Fig. 1 is a schematic diagram of a floating-body seismic isolation system according to a first embodiment. Fig. 2 is a partially enlarged view of a gas storage unit in the floating structure according to the first embodiment. Fig. 3 is a view of the damping member shown in Fig. 2 as seen in the direction of an arrow III. Fig. 4 is a partially enlarged view of a gas storage unit in a floating structure according to a second embodiment.

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation. Elements not directly related to the present disclosure are not shown.

[0016] (First embodiment) Fig. 1 is a schematic diagram of a floating seismic isolation system 100 according to a first embodiment. As shown in Fig. 1, the floating seismic isolation system 100 includes a liquid storage section 110 and a floating structure 120. In Fig. 1, the Z direction indicates the vertical direction, the X direction indicates a predetermined first direction among the horizontal directions, and the Y direction indicates a second direction perpendicular to the X direction, which is the first direction among the horizontal directions.

[0017] The liquid storage section 110 includes a recess 112 that is recessed vertically downward in the Z direction. Water 114 is stored in the recess 112. The water 114 may be natural water such as rainwater, groundwater, spring water, seawater, lake water, or spring water, or may be artificially treated water such as tap water, industrial water, commercial water, or agricultural water. However, the water 114 is not limited thereto, and may be, for example, an aqueous solution in which a substance is dissolved in water, or any other liquid other than water.

[0018] The floating structure 120 is arranged to float in the water 114 stored in the liquid storage portion 110. The floating structure 120 is arranged to be spaced apart in the X direction, the Y direction, and the Z direction from the recessed portion 112, which is the wall of the liquid storage portion 110.

[0019] The floating structure 120 is, for example, a floating nuclear power plant. However, the floating structure 120 is not limited to this, and may be a structure for other plants such as a wind power plant, a wave power plant, or a solar power plant, or may be a structure on which any other equipment is mounted. In this embodiment, the floating structure 120 is, for example, a floating plant floating on an artificial lake, but may also be an offshore plant floating on the sea.

[0020] The floating structure 120 includes a float 130 and a plurality of gas storage units 140. The float 130 is a block configured to be able to float on the water 114. The material of the float 130 may include, for example, a metal member such as a steel plate, a plastic resin material such as a fiber-reinforced thermosetting resin, or reinforced concrete. The density of the material of the float 130 may be lower than the density of a liquid such as water. The float 130 may have, for example, a rectangular parallelepiped shape as shown in the figure, but may also have a disk shape, a cylindrical shape, an elliptical cylinder shape, a polygonal prism shape, or the like. The float 130 has an upper surface 130a, a side surface 130b, and a lower surface 130c.

[0021] The upper surface 130a is a rectangular surface of the float 130 that faces vertically upward. The side surface 130b is a rectangular surface of the float 130 that faces horizontally. A pair of side surfaces 130b is formed in the X direction, and a pair of side surfaces 130b is formed in the Y direction. The lower surface 130c is a rectangular surface of the float 130 that faces vertically downward. The portion of the float 130 that faces the lower surface 130c, which floats on the water 114, is in contact with the water 114. In other words, the portion of the float 130 that faces the lower surface 130c is the portion that comes into contact with the water 114.

[0022] The gas storage section 140 is provided in a portion of the float 130 that comes into contact with the water 114. The gas storage section 140 is a space that stores gas that can be compressed and changed by receiving vibrations from the water 114. In other words, the volume and pressure of the stored gas can be changed by receiving vibrations from the water 114. In the first embodiment, an example will be described in which the gas stored in the gas storage section 140 is air, which is a mixed gas of multiple pure gases. However, the gas is not limited to this, and the gas stored in the gas storage section 140 may be, for example, a pure gas such as nitrogen, oxygen, or hydrogen, or any other gas other than air.

[0023] The gas storage section 140 is provided at a location of the float 130 that comes into contact with the water 114, and is therefore formed in a sealed manner between the float 130 and the water 114. In this embodiment, the gas storage section 140 is formed as a depression in the lower surface 130c of the float 130. An sealed space is formed within the gas storage section 140. The sealed space is a space surrounded by five wall surfaces of the gas storage section 140 and the liquid surface of the water 114.

[0024] In the first embodiment, the floating structure 120 has a plurality of gas storage sections 140. For example, in the example of Fig. 1, four gas storage sections 140 are formed side by side in the X direction on the underside 130c of the floating structure 120, and two sets of four gas storage sections 140 are formed side by side in the Y direction (not shown). In other words, a total of eight gas storage sections 140 are formed in the floating structure 120 of the first embodiment. However, this is not limited to this, and the number of gas storage sections 140 may be one, or any number equal to or greater than two.

[0025] 2 is a partially enlarged view of the gas storage section 140 in the floating structure 120 according to the first embodiment. The gas storage section 140 is formed, for example, by a rectangular parallelepiped recess recessed vertically upward from the lower surface 130c of the float 130. However, without being limited thereto, the gas storage section 140 may be formed, for example, by a polygonal prism-shaped recess or a cylindrical recess.

[0026] As shown in FIG. 2 , the gas storage section 140 has an upper wall 140a, a side wall 140b, and an opening 140c. The upper wall 140a is a rectangular wall formed in the vertically upward direction of the gas storage section 140. The side wall 140b is a rectangular wall formed in the horizontal direction of the gas storage section 140. A pair of side walls 140b is formed in the X direction, and a pair of side walls 140b is formed in the Y direction. The opening 140c is formed in a rectangular shape and is formed in the vertically downward direction of the gas storage section 140. The gas storage section 140 opens to the lower surface 130c of the float 130. In this embodiment, the opening provided in the lower surface 130c is submerged in the liquid surface. In other words, the liquid surface is located closer to the gas storage section 140 than the opening.

[0027] When an earthquake occurs, longitudinal waves (compression waves) caused by the earthquake propagate through the fluid containing the water 114 and the air in the gas storage section 140, exciting the response of the floating structure 120 and causing the floating structure 120 to vibrate violently.

[0028] Here, the natural vibration characteristics of the wave propagating through the fluid depend on the bulk modulus (hereinafter referred to as equivalent bulk modulus) of the entire fluid, which is the combination of the water 114 and the air in the gas storage portion 140. Therefore, in order to adjust this equivalent bulk modulus, the volume of the space in the gas storage portion 140 is adjusted.

[0029] For example, the larger the volume of the space within the gas storage section 140, the smaller the equivalent bulk modulus, and the smaller the natural frequency of the system that responds to seismic waves. Here, the natural frequency of the system that responds to seismic waves is the natural frequency when the float 130, the water 114, and the air within the gas storage section 140 act as a single system. By adjusting the volume of the space within the gas storage section 140, the natural frequency of the system that responds to seismic waves can be separated from the natural frequency of the floating structure 120. As a result, excitation of the floating structure 120 due to an earthquake can be reduced.

[0030] In the first embodiment, an orifice 150 is disposed in the space within the gas storage section 140. The orifice 150 is an example of a damping member. Here, the damping member is a flat plate-shaped member disposed in the space within the gas storage section 140, and is a member that damps vibrations of the floating structure 120 caused by seismic waves. The orifice 150 is provided in the side wall 140b of the gas storage section 140. For example, the orifice 150 is provided in the center of the side wall 140b in the Z direction.

[0031] Fig. 3 is a view of the orifice 150 shown in Fig. 2 as viewed in the direction of arrow III. As shown in Fig. 3, the orifice 150 is formed, for example, in the shape of a rectangular flat plate, and a communicating hole 152 with a circular cross section extending in the Z direction is formed in the center of the XY plane. As shown in Fig. 2, the orifice 150 has an upper surface 150a and a lower surface 150b. The communicating hole 152 is a through-hole that penetrates the orifice 150 from the upper surface 150a to the lower surface 150b.

[0032] In the first embodiment, the number of communication holes 152 formed in the orifice 150 is, for example, one. However, this is not limited to this, and the number of communication holes 152 formed in the orifice 150 may be multiple. In other words, the orifice 150 has at least one communication hole 152 formed therein.

[0033] The orifice 150 functions as a throttle structure that reduces the horizontal cross-sectional area of ​​the gas accommodating section 140. However, without being limited thereto, the orifice 150 may be any damping member that attenuates vibrations of the floating structure 120 caused by seismic waves, and may be, for example, a punched metal or a foamed metal. The punched metal and the foamed metal have a plurality of communicating holes and function as a throttle structure that reduces the horizontal cross-sectional area of ​​the gas accommodating section 140.

[0034] Returning to Fig. 2, the orifice 150 vertically divides the space within the gas storage section 140. The space within the gas storage section 140 is divided by the orifice 150 into a first space 142 on the vertically lower side and a second space 144 on the vertically upper side. In other words, the orifice 150 is provided between the first space 142 and the second space 144. Furthermore, the communication hole 152 communicates the first space 142 with the second space 144. The orifice 150 is an element for attenuating vibrations of air transmitted from the first space 142 to the second space 144.

[0035] The first space 142 is provided on the lower surface 130c of the float 130, which contacts the water 114. The first space 142 is recessed from the lower surface 130c of the float 130. The first space 142 is connected to an opening 140c formed in the lower surface 130c of the float 130. Therefore, the first space 142 is in communication with the opening 140c in the lower surface 130c of the float 130.

[0036] The second spaces 144 are spaces provided inside the float 130 and communicate with the first spaces 142 via the communication holes 152. One first space 142 communicates with one second space 144. One first space 142 and one second space 144 that communicate with each other form a pair. As described above, a plurality of gas accommodating sections 140 are formed inside the float 130. Therefore, a plurality of pairs of first spaces 142 and second spaces 144 are provided inside the float 130.

[0037] As described above, in the first embodiment, the orifice 150 is disposed in the space within the gas storage section 140. As a result, resistance is generated when air passes through the communication hole 152 of the orifice 150, and this resistance acts as a damping force in the vibration response caused by the transmission of seismic waves to the floating structure 120. This damping force can suppress the vibration response of the floating structure 120 caused by the transmission of seismic waves.

[0038] However, seismic waves vibrate the air in the gas storage section 140, and in particular, when the air passes through the communication hole 152 of the orifice 150, air column vibrations and acoustic vibrations occur, which may reduce the seismic isolation performance of the floating structure 120.

[0039] Therefore, the floating structure 120 according to the first embodiment has a sound-absorbing material 160 and a protective film 170 provided in the gas storage section 140 as shown in Fig. 2. The sound-absorbing material 160 is a perforated plate or a porous plate having holes smaller than the communication holes 152. In the first embodiment, the sound-absorbing material 160 is, for example, glass wool.

[0040] In the first embodiment, the sound absorbing material 160 is provided in the second space 144, but not in the first space 142. However, this is not limitative, and the sound absorbing material 160 may be provided in both the second space 144 and the first space 142. In other words, the sound absorbing material 160 is provided in at least the second space 144.

[0041] The sound absorbing material 160 has an upper portion 160a, a side portion 160b, and a lower portion 160c. The upper portion 160a is provided on the upper wall 140a of the gas accommodating portion 140, and the side portion 160b is provided on the side wall 140b of the gas accommodating portion 140. The lower portion 160c is provided on the upper surface 150a, which is the surface of the orifice 150. In the first embodiment, the upper portion 160a, the side portion 160b, and the lower portion 160c are integrally formed.

[0042] However, without being limited thereto, the upper portion 160 a, the side portion 160 b, and the lower portion 160 c may be formed separately. Furthermore, at least one of the upper portion 160 a, the side portion 160 b, and the lower portion 160 c may be provided within the second space 144.

[0043] For example, the upper portion 160a may be formed in the second space 144, but the side portion 160b and the lower portion 160c may not be formed. Alternatively, the side portion 160b may be formed in the second space 144, but the upper portion 160a and the lower portion 160c may not be formed. Alternatively, the lower portion 160c may be formed in the second space 144, but the upper portion 160a and the side portion 160b may not be formed. Alternatively, the upper portion 160a and the side portion 160b may be formed in the second space 144, but the lower portion 160c may not be formed. Alternatively, the side portion 160b and the lower portion 160c may be formed in the second space 144, but the upper portion 160a may not be formed. Alternatively, the upper portion 160a and the lower portion 160c may be formed in the second space 144, but the side portion 160b may not be formed.

[0044] The sound absorbing material 160 has an upper portion 160a, a side portion 160b, and a lower portion 160c that have the same thickness. However, the present invention is not limited thereto, and the upper portion 160a, the side portion 160b, and the lower portion 160c may have different thicknesses.

[0045] The sound-absorbing material 160 has sound-absorbing properties and attenuates the energy of acoustic vibrations generated when the air in the gas storage section 140 is vibrated by seismic waves, thereby reducing the response of the floating structure 120 due to acoustic vibrations.

[0046] The protective film 170 is a film that has liquid-proof properties. For example, the protective film 170 is a film that has waterproof properties. The protective film 170 is provided on the surface of the sound-absorbing material 160. Specifically, the protective film 170 is provided on the surfaces of the upper portion 160a, the side portion 160b, and the lower portion 160c of the sound-absorbing material 160 that come into contact with the air in the gas accommodating portion 140.

[0047] However, without being limited thereto, the protective film 170 may be provided, for example, only on the surface of the upper portion 160a that comes into contact with the air inside the gas accommodating portion 140. Furthermore, the protective film 170 may be provided, for example, only on the surface of the side portion 160b that comes into contact with the air inside the gas accommodating portion 140. Furthermore, the protective film 170 may be provided, for example, only on the surface of the lower portion 160c that comes into contact with the air inside the gas accommodating portion 140. In this way, the protective film 170 may be provided on at least a portion of the surface of the sound-absorbing material 160.

[0048] When water 114 enters the space inside gas accommodating section 140, protective film 170 prevents contact between sound absorbing material 160 and water 114. This prevents water 114 from blocking the pores of sound absorbing material 160 and reducing the sound absorbing performance of sound absorbing material 160.

[0049] As described above, according to the first embodiment, the gas storage section 140 includes the orifice 150 having at least one communication hole 152 that communicates the first space 142 and the second space 144, and the sound-absorbing material 160 that is provided in at least the second space 144. This makes it possible to attenuate the energy of acoustic vibrations that are generated when the air in the gas storage section 140 is excited by seismic waves, and to reduce the response of the floating structure 120 due to the acoustic vibrations. As a result, it is possible to suppress a decrease in the seismic isolation performance of the floating structure 120.

[0050] Furthermore, in the first embodiment, the floating structure 120 has an orifice 150 provided between the first space 142 and the second space 144. By disposing the orifice 150 in the space within the gas storage section 140, resistance is generated when air passes through the communication hole 152 of the orifice 150. This resistance acts as a damping force in the vibration response caused by the transmission of seismic waves to the floating structure 120. This damping force can suppress the vibration response of the floating structure 120 caused by the transmission of seismic waves.

[0051] In the first embodiment, the sound absorbing material 160 is a perforated plate or a porous plate having holes smaller than the communication holes 152 of the orifice 150. The sound absorbing material 160 has minute holes smaller than the communication holes 152 of the orifice 150, so that the energy of acoustic vibrations generated in the gas storage section 140 can be attenuated.

[0052] Furthermore, in the first embodiment, a protective film 170 having liquid-proof properties is provided on at least a portion of the surface of the sound-absorbing material 160. This prevents water 114 from blocking the pores of the sound-absorbing material 160 and reducing the sound-absorbing performance of the sound-absorbing material 160.

[0053] Furthermore, in the first embodiment, the sound absorbing material 160 is provided on the surface of the orifice 150. That is, the sound absorbing material 160 is arranged on the surface of the orifice 150 in addition to the top wall 140a and the side wall 140b, which are the inner walls of the gas containing section 140. This makes it possible to improve the sound absorbing effect compared to when the sound absorbing material 160 is not arranged on the surface of the orifice 150.

[0054] Furthermore, in the first embodiment, a plurality of pairs of first spaces 142 and second spaces 144 are provided inside the float 130. In other words, a plurality of gas storage sections 140 are provided in the float 130. This allows the amount of air in each gas storage section 140 to be adjusted individually, and allows the float 130 to float more stably than when there is only one gas storage section 140.

[0055] Second Embodiment Figure 4 is a partially enlarged view of the gas storage section 140 of a floating structure 220 according to a second embodiment. Components that are substantially the same as those of the floating structure 120 according to the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted. In the second embodiment, the sound-absorbing material 160 includes an upper portion 160a, a side portion 160b, and a lower portion 160c that are arranged in the second space 144, as well as an upper portion 160d and a side portion 160e that are arranged in the first space 142. In this respect, the floating structure 220 according to the second embodiment differs from the floating structure 120 according to the first embodiment. The remaining configuration is the same as that of the floating structure 120 according to the first embodiment.

[0056] 4, of the sound absorbing material 160, an upper portion 160a, a side portion 160b, and a lower portion 160c are disposed in the second space 144. Furthermore, of the sound absorbing material 160, an upper portion 160d and a side portion 160e are disposed in the first space 142. The upper portion 160d disposed in the first space 142 is provided on the lower surface 150b, which is the surface of the orifice 150. Furthermore, the side portion 160b disposed in the first space 142 is provided on the side wall 140b of the gas accommodating portion 140. In the second embodiment, the upper portion 160d and the side portion 160e are integrally formed.

[0057] However, the present invention is not limited to this, and the upper portion 160d and the side portion 160e may be formed separately. Also, either the upper portion 160d or the side portion 160e may be provided within the first space 142.

[0058] For example, the upper portion 160d may be formed in the first space 142, but the side portion 160e may not be formed. Alternatively, the side portion 160e may be formed in the first space 142, but the upper portion 160d may not be formed.

[0059] The upper portion 160d and the side portion 160e of the sound absorbing material 160 have the same thickness, but are not limited thereto, and the upper portion 160d and the side portion 160e may have different thicknesses.

[0060] The side portion 160e arranged in the first space 142 is spaced in the Z direction from the opening 140c in the underside 130c of the float 130. Therefore, even if the water 114 enters the first space 142 from the opening 140c when the float 130 is floated on the water 114, contact between the water 114 and the side portion 160e can be suppressed.

[0061] The protective film 170 is provided on the surfaces of the sound absorbing material 160 that come into contact with the air in the gas containing portion 140, among the upper portions 160a and 160d, the side portions 160b and 160e, and the lower portion 160c.

[0062] However, without being limited thereto, the protective film 170 may be provided, for example, only on the surface of the upper portion 160a or the upper portion 160d that comes into contact with the air inside the gas accommodating portion 140. Furthermore, the protective film 170 may be provided, for example, only on the surface of the side portion 160b or the side portion 160e that comes into contact with the air inside the gas accommodating portion 140. Furthermore, the protective film 170 may be provided, for example, only on the surface of the lower portion 160c that comes into contact with the air inside the gas accommodating portion 140. In this way, the protective film 170 may be provided on at least a portion of the surface of the sound-absorbing material 160.

[0063] According to the second embodiment, the gas storage section 140 includes an orifice 150 having at least one communication hole 152 that communicates the first space 142 and the second space 144, and a sound-absorbing material 160 provided in both the first space 142 and the second space 144. Therefore, similar to the first embodiment, it is possible to suppress a decrease in the seismic isolation performance of the floating structure 120. Furthermore, in the second embodiment, the sound-absorbing material 160 is provided in the first space 142 in addition to the second space 144. This improves the effect of sound absorption compared to a case where the sound-absorbing material 160 is not provided in the first space 142.

[0064] Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present disclosure.

[0065] In the above embodiment, an example in which the protective film 170 is provided inside the gas storage unit 140 has been described, but the protective film 170 is not an essential component. Therefore, the protective film 170 does not necessarily have to be provided inside the gas storage unit 140.

[0066] The present disclosure can contribute, for example, to Sustainable Development Goal (SDG) Goal 7: "Ensure access to affordable, reliable, sustainable and modern energy."

[0067] REFERENCE SIGNS LIST 100 Floating seismic isolation system 110 Liquid storage section 114 Water (liquid) 120 Floating structure 140 Gas storage section 142 First space 144 Second space 150 Orifice (damping member) 152 Communication hole 160 Sound absorbing material 170 Protective film

Claims

1. A floating structure comprising: a float capable of floating on liquid; a first space provided in a portion of the float that comes into contact with the liquid; a second space provided inside the float and paired with the first space; a damping member having at least one communication hole that connects the first space with the second space; and a sound-absorbing material provided in at least the second space, wherein the first space and the second space are spaces that contain gas that can be compressed and deformed by vibrations from the liquid.

2. The floating structure according to claim 1, wherein the damping member is an orifice provided between the first space and the second space.

3. A floating structure according to claim 1 or 2, wherein the sound-absorbing material is a perforated or porous plate having holes smaller than the communicating holes.

4. A floating structure as set forth in claim 1 or 2, wherein a protective film having liquid-proof properties is provided on at least a part of the surface of the sound-absorbing material.

5. A floating structure according to claim 1 or 2, wherein the sound-absorbing material is provided on the surface of the damping member.

6. A floating structure according to claim 1 or 2, wherein a plurality of pairs of the first space and the second space are provided inside the float.

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